The distribution of differentiated phenotypes of chondrocytes in osteoarthritic knee.

Articular cartilage consists of chondrocytes and a cartilagenous matrix produced by these cells. The cartilaginous matrix is considered to undergo various changes in response to the surrounding environment. In this study, cartilaginous changes related to osteoarthritis of the knee were investigated. Histological changes were apparent in medical joint lesions, and changes typical of osteoarthritis, such as cell clustering and disruption of the matrix, were always observed. Degeneration was less severe in the lateral joint lesions. A biochemical analysis was undertaken and the molecular size of the proteoglycan produced in the matrix was measured by glycerol density gradient ultracentrifugation method, following pulse labeling with 35S-Sulfuric acid. The proteoglycan produced in the histologically altered regions tended to be of low molecular size. However, the size was still significantly larger than that of proteoglycans located in the nonarticular tissues such as synovia membrane, so the differentiated phenotype of chondrocytes persisted.